<?xml version="1.0" encoding="iso-8859-1"?>
<!DOCTYPE html 
     PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
     "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
<head>
  <title>Class: ETL</title>
  <meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1" />
  <meta http-equiv="Content-Script-Type" content="text/javascript" />
  <link rel="stylesheet" href=".././rdoc-style.css" type="text/css" media="screen" />
  <script type="text/javascript">
  // <![CDATA[

  function popupCode( url ) {
    window.open(url, "Code", "resizable=yes,scrollbars=yes,toolbar=no,status=no,height=150,width=400")
  }

  function toggleCode( id ) {
    if ( document.getElementById )
      elem = document.getElementById( id );
    else if ( document.all )
      elem = eval( "document.all." + id );
    else
      return false;

    elemStyle = elem.style;
    
    if ( elemStyle.display != "block" ) {
      elemStyle.display = "block"
    } else {
      elemStyle.display = "none"
    }

    return true;
  }
  
  // Make codeblocks hidden by default
  document.writeln( "<style type=\"text/css\">div.method-source-code { display: none }</style>" )
  
  // ]]>
  </script>

</head>
<body>



    <div id="classHeader">
        <table class="header-table">
        <tr class="top-aligned-row">
          <td><strong>Class</strong></td>
          <td class="class-name-in-header">ETL</td>
        </tr>
        <tr class="top-aligned-row">
            <td><strong>In:</strong></td>
            <td>
                <a href="../files/etl/std_rb.html">
                etl/std.rb
                </a>
        <br />
            </td>
        </tr>

        <tr class="top-aligned-row">
            <td><strong>Parent:</strong></td>
            <td>
                Object
            </td>
        </tr>
        </table>
    </div>
  <!-- banner header -->

  <div id="bodyContent">



  <div id="contextContent">

    <div id="description">
      <p>
This class defines properties and methods which are shared among all <a
href="ETL.html">ETL</a> block implementations. All implementation should
derive from this class.
</p>
<h2>Defining an <a href="ETL.html">ETL</a> block</h2>
<p>
In order to be properly inserted within a chain (such as <b><a
href="ETL.html#M000062">extract</a></b> , <b><a
href="ETL.html#M000063">transform</a></b> or <b><a
href="ETL.html#M000064">load</a></b> chains) implementations should define
the proper callback method, and added to the chain configuration. The
callback method MUST adhere to this signature:
</p>
<pre>
 def [chain_name](dto, context)
   implementation
 end
</pre>
<p>
where <tt>[chain_name]</tt> is the name of the chain the block will belong
to. For example
</p>
<pre>
 class MyETL &lt; ETL
   def extract(dto,context)
     my_extract_impl
   end
 end
</pre>
<p>
The parameters <tt>dto</tt> and <tt>context</tt> respectively represent the
Data Transfer Object (DTO) associated to this <a href="ETL.html">ETL</a>
run and the execution context.
</p>
<p>
Implementations may define multiple callbacks, if they can be inserted into
multiple chains (for example, an <a href="ETL.html">ETL</a> block may
implement both <tt><a href="ETL.html#M000062">extract</a></tt> and <tt><a
href="ETL.html#M000063">transform</a></tt> if it can work in both chains)
</p>
<p>
See the documentation for <a href="ETLRunner.html">ETLRunner</a> for
further info.
</p>

    </div>


   </div>

    <div id="method-list">
      <h3 class="section-bar">Methods</h3>

      <div class="name-list">
      <a href="#M000062">extract</a>&nbsp;&nbsp;
      <a href="#M000064">load</a>&nbsp;&nbsp;
      <a href="#M000063">transform</a>&nbsp;&nbsp;
      </div>
    </div>

  </div>


    <!-- if includes -->
    <div id="includes">
      <h3 class="section-bar">Included Modules</h3>

      <div id="includes-list">
        <span class="include-name"><a href="Log.html">Log</a></span>
      </div>
    </div>

    <div id="section">





    <div id="attribute-list">
      <h3 class="section-bar">Attributes</h3>

      <div class="name-list">
        <table>
        <tr class="top-aligned-row context-row">
          <td class="context-item-name">name</td>
          <td class="context-item-value">&nbsp;[RW]&nbsp;</td>
          <td class="context-item-desc">
The etl name. Implementations should not override this property, since the
<a href="ETL.html">ETL</a> name is managed via the <a
href="ETL.html">ETL</a> configuration file.

</td>
        </tr>
        <tr class="top-aligned-row context-row">
          <td class="context-item-name">props</td>
          <td class="context-item-value">&nbsp;[RW]&nbsp;</td>
          <td class="context-item-desc">
The block configuration properties. Implementations should not override
this property, since the <a href="ETL.html">ETL</a> properties are managed
via the <a href="ETL.html">ETL</a> configuration file.

</td>
        </tr>
        </table>
      </div>
    </div>
      


    <!-- if method_list -->
    <div id="methods">
      <h3 class="section-bar">Public Instance methods</h3>

      <div id="method-M000062" class="method-detail">
        <a name="M000062"></a>

        <div class="method-heading">
          <a href="ETL.src/M000062.html" target="Code" class="method-signature"
            onclick="popupCode('ETL.src/M000062.html');return false;">
          <span class="method-name">extract</span><span class="method-args">(dto,context)</span>
          </a>
        </div>
      
        <div class="method-description">
          <p>
An empty implementation of the <tt><a
href="ETL.html#M000062">extract</a></tt> operation. It raises a warning
when invoked (since you are supposed to have overriden it)
</p>
        </div>
      </div>

      <div id="method-M000064" class="method-detail">
        <a name="M000064"></a>

        <div class="method-heading">
          <a href="ETL.src/M000064.html" target="Code" class="method-signature"
            onclick="popupCode('ETL.src/M000064.html');return false;">
          <span class="method-name">load</span><span class="method-args">(dto,context)</span>
          </a>
        </div>
      
        <div class="method-description">
          <p>
An empty implementation of the <tt><a href="ETL.html#M000064">load</a></tt>
operation. It raises a warning when invoked (since you are supposed to have
overriden it)
</p>
        </div>
      </div>

      <div id="method-M000063" class="method-detail">
        <a name="M000063"></a>

        <div class="method-heading">
          <a href="ETL.src/M000063.html" target="Code" class="method-signature"
            onclick="popupCode('ETL.src/M000063.html');return false;">
          <span class="method-name">transform</span><span class="method-args">(dto,context)</span>
          </a>
        </div>
      
        <div class="method-description">
          <p>
An empty implementation of the <tt><a
href="ETL.html#M000063">transform</a></tt> operation. It raises a warning
when invoked (since you are supposed to have overriden it)
</p>
        </div>
      </div>


    </div>


  </div>


<div id="validator-badges">
  <p><small><a href="http://validator.w3.org/check/referer">[Validate]</a></small></p>
</div>

</body>
</html>